Liquid stabilizing mixtures for organic polymers

ABSTRACT

Liquid stabilizing mixtures for organic polymers comprising: a) a liquid compound belonging to the group of sterically hindered phenols consisting of esters or mixtures of esters having formula (I); b) a solid compound belonging to the group of sterically hindered phenols having formula (II).

The present invention relates to liquid stabilizing mixtures for organic polymers.

More specifically, the present invention relates to liquid stabilizing mixtures for organic polymers comprising a liquid compound belonging to the group of sterically hindered phenols and a solid compound belonging to the group of sterically hindered phenols and their use in the stabilization of organic polymers to degradation caused by oxygen, heat and/or light.

The present invention also relates to the polymeric compositions stabilized with the above stabilizing mixtures and the end-products obtained by their processing.

It is known that the use of additives in the solid state often causes various problems. For example, in some cases, additives in the solid state which are in the form of crystalline powders, flakes or drops in the vitreous state, are ground to very fine powders before being added to latex emulsions of natural or synthetic rubber to prevent granules of additives from remaining in the end-product after coagulation of the latex, drying and vulcanization.

Another disadvantage is the addition of an additive in the solid state in a process in which said additive is added in a particular processing step such as, for example, during the mixing of copolymers, or during polymerization and/or copolymerization. This problem arises, for example, when the solid stabilizer must be added to a solution or emulsion of a polymer at the end of the polymerization such as, for example, in the preparation of the following polymers: polyols, polyurethanes, nitrile rubbers, SBR, polyisoprene, polybutadiene, ABS, PVC, etc. In these cases, it is necessary to separately prepare a solution of the additive in a suitable organic solvent or an aqueous dispersion thereof and add said solution or dispersion to the solution or emulsion of the polymer.

The Applicant has now found liquid stabilizing mixtures comprising a liquid compound belonging to the group of sterically hindered phenols and a solid compound belonging to the group of sterically hindered phenols which are capable of overcoming the drawbacks of the known art. These mixtures are capable of permanently remaining liquid, both at room temperature and at temperatures lower than 0° C. (for example, as low as −30° C.), and can consequently be used whenever the addition of a stabilizer in solid form is particularly complex.

An object of the present invention therefore relates to liquid stabilizing mixtures for organic polymers comprising:

-   -   (a) a liquid compound belonging to the group of sterically         hindered phenols consisting of esters or mixtures of esters         having general formula (I):

wherein:

-   -   R₁ and R₂, the same or different, represent a linear or branched         C₁-C₁₈ alkyl group;     -   R₃ represents a linear or branched C₈-C₁₈ alkyl group, or one of         the following groups:

-   -   -   wherein m and n are an integer ranging from 0 to 11,             extremes included; and m+n is 10 or 11;         -   and p is 12 or 13;

    -   (b) a solid compound belonging to the group of sterically         hindered phenols having formula (II):

-   -   -   wherein n is an integer ranging from 0 to 10, extremes             included.

Examples of linear or branched C₁-C₁₈ alkyl groups are: methyl, ethyl, propyl, isopropyl, butyl, 2-butyl, isobutyl, t-butyl, pentyl, 2-pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, t-octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, etc.

Preferred liquid compounds belonging to the group of sterically hindered phenols (a) for the purposes of the present invention are those wherein R₁ and R₂, the same or different, are: methyl, ethyl, isopropyl, t-butyl; and R₃ represents one of the following groups:

wherein m, n and p have the same meanings defined above.

Specific examples of liquid compounds belonging to the group of sterically hindered phenols (a) useful for the purposes of the present invention are Anox ® BF (a sterically hindered phenol) of Great Lakes Chemical Corporation and Irganox ® (a sterically hindered phenol) 1135 of Ciba.

A specific example of a solid compound belonging to the group of sterically hindered phenols (b) useful for the purposes of the present invention is Lowinox ® CPL (a polymeric sterically hindered phenol) of Great Lakes Chemical Corporation, also known as Wingstay ® L (a polymeric sterically hindered phenol) of Goodyear.

The liquid compounds belonging to the group of sterically hindered phenols (a) are commercial compounds or, they can be prepared by the transesterification of a methyl ester having general formula (III)

wherein R₁ and R₂ have the same meanings described above, with an alcohol or a mixture of alcohols having general formula (IV): R₃—OH   (IV) wherein R₃ has the same meanings described above, in the presence of catalysts based on tin or zinc such as, for example, dibutyl tin dilaurate, dibutyl tin oxide, zinc octanoate, etc., as described, for example, in the patent EP 502,520.

The solid compound belonging to the group of sterically hindered phenols (b) is a commercial product or, it can be prepared by the reaction of p-cresol with dicyclopentadiene and subsequent alkylation with isobutylene, in the presence of acid catalysts such as, for example, boron trifluoride, methanesulfonic acid, p-toluene-sulfonic acid, etc., as described, for example, in the patent GB 1,068,995.

The liquid stabilizing mixtures, object of the present invention, can be prepared by means of various processes.

One process for the preparation of the above liquid stabilizing mixtures comprises:

-   (a′) heating the liquid compound belonging to the group of     sterically hindered phenols (a) to a temperature ranging from 60° C.     to 180° C., under stirring; -   (b′) adding the solid compound belonging to the group of sterically     hindered phenols (b), maintaining the temperature within the range     of 60° C. to 180° C., preferably from 90° C. to 140° C., and     maintaining the whole mixture under stirring until the complete     dissolution of said compound (b), for a time ranging from 5 minutes     to 100 minutes, preferably from 10 minutes to 60 minutes, obtaining     a liquid mixture.

The liquid mixture thus obtained is discharged into drums or tanks and remains permanently liquid, without re-precipitations of the solid compound belonging to the group of sterically hindered phenols (b), both at room temperature and at temperatures lower than 0° C. as already specified above.

The weight ratios between the liquid compound belonging to the group of sterically hindered phenols (a), and the solid compound belonging to the group of sterically hindered phenols (b) range from 90:10 to 30:70, preferably from 80:20 to 50:50, even more preferably from 60:40 to 70:30.

In an alternative process, at the end of the preparation procedure of the solid compound belonging to the group of sterically hindered phenols (b) obtained as described in patent GB 1,068,995 which forms an integrant part of the present patent application, and more specifically, after neutralization of the catalyst used, neutral washings and distillation of the reaction solvent, before pouring said liquid compound (b), melted at 175° C., on a tape and cooling it to obtain drops or flakes, the liquid compound belonging to the group of sterically hindered phenols (a) is added directly; the procedure is carried out under stirring and under the same operating conditions as step (b′) described above, obtaining the liquid stabilizing mixture desired.

The liquid stabilizing mixtures, object of the present invention, are capable of stabilizing organic polymers against degradation caused by oxygen, heat and/or light. Examples of organic polymers to which they can be added are:

-   1. Polymers of mono-olefins and di-olefins such as, for example,     polypropylene, polyisobutylene, polybut-1-ene,     poly-4-methylpent-1-ene, polyisoprene or polybutadiene; as well as     polymers of cyclo-olefins such as, for example, cyclopentene or     norbornene; polyethylene (which can be optionally cross-linked) such     as, for example, high density polyethylene (HDPE), high density and     high molecular weight polyethylene (HDPE-HMW), high density and     ultrahigh molecular weight polyethylene (HDPE-UHMN), medium density     polyethylene (MDPE), low density polyethylene (LDPE), linear low     density polyethylene (LLDPE), branched low density polyethylene     (BLDPE), (VLDPE), (ULDPE).

Polyolefins such as, for example the mono-olefins mentioned in the above paragraph, preferably polyethylene and polypropylene, can be prepared with many methods known in literature, preferably using the following methods:

-   a) radicalic polymerization (generally carried out at a high     pressure and high temperature); -   (b) catalytic polymerization using a catalyst which normally     contains one or more metals of groups IVb, Vb, VIb or VIII of the     Periodic Table. These metals generally have one or more ligands such     as, for example, oxides, halides, alcoholates, esters, ethers,     amines, alkyls, alkenyls and/or aryls which can be π- or     σ-coordinated. These metal complexes can be in free form or     supported on substrates such as, for example, activated magnesium     chloride, titanium(III) chloride,, alumina or silicon oxide. Said     catalysts can be soluble or insoluble in the polymerization medium.     The catalysts can be used alone or in the presence of other     activators such as, for example, metal alkyls, metal hydrides,     halides of metal alkyls, oxides of metal alkyls or metal     alkyloxanes, these metals being elements belonging to groups Ia, IIa     and/or IIIa of the Periodic Table. The activators can be     conveniently modified with other ester, ether, amine or silyl-ether     groups. These catalytic systems are usually called Phillips,     Standard Oil Indiana, Ziegler(-Natta), TNZ (Du-Pont), metallocene or     “single site catalyst” (SSC). -   2. Mixtures of the polymers described under point (1) such as, for     example, mixtures of polypropylene with polyisobutylene; mixtures of     polypropylene with polyethylene (for example, PP/HDPE, PP/LDPE);     mixtures of different types of polyethylene (for example,     LDPE/HDPE). -   3. Copolymers of mono-olefins and di-olefins with each other or with     other vinyl monomers such as, for example, ethylene/propylene     copolymers, linear low density polyethylene (LLDPE) and its mixtures     with low density polyethylene (LDPE), propylene/but-1-ene     copolymers, propylene/isobutylene copolymers, ethylene/but-1-ene     copolymers, ethylene/hexene copolymers, ethylene/methylpentene     copolymers, ethylene/heptene copolymers, ethylene/octene copolymers,     propylene/butadiene copolymers, isobutylene/isoprene copolymers,     ethylene/alkyl acrylate copolymers, ethylene/alkyl methacrylate     copolymers, ethylene/vinyl acetate copolymers and their copolymers     with carbon monoxide or ethylene/acrylic acid copolymers and their     salts (ionomers) as well as terpolymers of ethylene with propylene     and a diene such as, for example, hexadiene, dicyclopentadiene or     ethylidene-norbornene; and also mixtures of said copolymers with     each other or with the polymers cited in under point (1) such as,     for example, polypropylene/ethylene/propylene copolymers,     LDPE/ethylene/vinylacetate. (EVA) copolymers, LDPE/ethylene/acrylic     acid (EAA) copolymers, LLDPE/EVA, LLDPE/EAA, and alternating or     random polyalkylene/carbon monoxide copolymers and their mixtures     with other polymers such as, for example, polyamides. -   4. Hydrocarbon resins (for example, C₅-C₉) comprising their     hydrogenated modifications (for example, adhesive resins) and     mixtures with polyalkylene and starch. -   5. Polystyrene, poly(p-methylstyrene), poly(α-methylstyrene). -   6. Copolymers of styrene or α-methylstyrene with dienes or acrylic     derivatives such as, for example, styrene/butadiene,     styrene/acrylonitrile, styrene/alkyl methacrylate,     styrene/butadiene/alkyl acrylate, styrene/ butadiene/alkyl     methacrylate, styrene/maleic anhydride, styrene/acrylonitrile/methyl     acrylate; mixtures, having a high tensile strength, between     copolymers of styrene and another polymer such as, for example, a     polyacrylate, a polymer of a diene or an ethylene/propylene/diene     terpolymer, block copolymers of styrene such as, for example,     styrene/butadiene/styrene, styrene/isoprene/styrene,     styrene/ethylene/butylene/styrene or     styrene/ethylene/propylene/styrene. -   7. Grafted copolymers of styrene or of α-methylstyrene such as, for     example, styrene in polybutadiene, styrene in polybutadiene/styrene     or polybutadiene/acrylonitrile copolymers; styrene and acrylonitrile     (or methacrylonitrile) in polybutadiene; styrene, acrylonitrile and     methylmethacrylate in polybutadiene; styrene and maleic anhydride in     polybutadiene; styrene, acrylonitrile and maleic anhydride or     maleimide in polybutadiene; styrene and maleimide in polybutadiene;     styrene and alkylacrylates or alkylmethacrylates in polybutadiene;     styrene and acrylonitriue in ethylene/propylene/diene terpolymers,     styrene and acrylonitrile in polyalkyl acrylates or polyalkyl     methacrylates, styrene and acrylonitrile in acrylate/butadiene     copolymers, as well as mixtures of the copolymers listed above with     the copolymers cited under point (6) such as, for example, mixtures     of known copolymers such as ABS, MBS, ASA or AES. -   8. Polymers containing halogens such as, for example,     polychloroprene, chlorinated rubbers, chlorinated or brominated     isobutylene-isoprene copolymers (“halobutyl rubber”), chlorinated or     chlorosulfonated polyethylene, ethylene and chlorinated ethylene     copolymers, homopolymers and copolymers of epichlorohydrin, in     particular polymers of vinyl compounds containing halogens such as,     for example, polyvinyl chloride, polyvinylidene chloride, polyvinyl     fluoride or polyvinylidene fluoride; and also their copolymers such     as, for example, vinyl chloride/vinylidene chloride, vinyl     chloride/vinyl acetate or vinylidene chloride/vinyl acetate. -   9. Polymers deriving from α,β-unsaturated acids and their     derivatives such as, for example, polyacrylates and     polymethacrylates, polymethyl methacrylates, polyacrylamides and     polyacrylonitriles, impact modified with butyl acrylate. -   10. Copolymers of monomers according to point (9) with each other or     with other unsaturated monomers such as, for example,     acrylonitrile/butadiene copolymers, acrylonitrile/alkyl acrylate     copolymers, acrylonitrile/alkoxyalkyl acrylate copolymers or     acrylonitrile/vinyl halide copolymers or acrylonitrile/alkyl     methacrylate/butadiene terpolymers. -   11. Polymers deriving from unsaturated alcohols and amines, or their     acyl or acetal derivatives such as, for example, polyvinyl alcohol,     polyvinyl acetate, polyvinyl stearate, polyvinyl benzoate, polyvinyl     maleate, polyvinyl butyral, polyallyl phthalate or polyallyl     melamine; and also their copolymers with the olefins listed under     point (1) -   12. Homopolymers and copolymers of open-chain ethers or cyclic     ethers such as, for example, polyalkylene glycols, polyethylene     oxide, polypropylene oxide, or copolymers of the compounds described     above with bis-glycidyl ethers. -   13. Polyacetals such as, for example, polyoxymethylene and those     polyoxymethylenes containing comonomers, for example, ethylene     oxide; polyacetals modified with thermoplastic polyurethanes,     acrylates or MBS. -   14. Polyphenylene oxides and sulfides and their mixtures with     styrene polymers or polyamides. -   15. Polyurethanes deriving from hydroxyl-terminated polyethers,     polyesters or polybutadienes on the one hand and aliphatic or     aromatic polyisocyanates on the other, as well as their precursors. -   16. Polyamides and copolyamides deriving from diamines and     dicarboxylic acids and/or aminocarboxylic acids or from the     corresponding lactams such as, for example, polyamide 4, polyamide     6, polyamide 6/6, 6/10, 6/9, 6/12, 4/6, 12/12, polyamide 11,     polyamide 12, aromatic polyamides obtained starting from m-xylene     diamine and adipic acid; polyamides prepared from     hexamethylenediamine and isophthalic and/or terephthalic acid and     with or without an elastomer as modifier, for example,     poly-2,4,4-trimethylhexamethylene terephthalamide or     poly-m-phenylene isophthalamide; and also block copolymers of the     above polyamides with polyolefins, olefinic copolymers, ionomers or     elastomers chemically bound or grafted; or with polyethers such as,     for example, polyethylene glycol, polypropylene glycol or     polytetramethylene glycol; as well as polyamides or copolyamides     modified with EPDM or ABS; and polyamides condensed during     processing (“RIM polyamide system”). -   17. Polyureas, polyimides, polyamide-imides, polyetherimides,     polyesterimides, polyhydantoins, and polybenzoimidazoles. -   18. Polyesters deriving from dicarboxylic acids and diols and/or     from hydroxycarboxylic acids or from the corresponding lactones such     as, for example, polyethylene terephthalate, polybutylene     terephthalate, poly-1,4-dimethylolcyclohexane terephthalate and     polyhydroxybenzoates, as well as block copolyether esters deriving     from polyethers with hydroxyl-terminated groups; and also polyesters     modified with polycarbonates or MBS. -   19. Polycarbonates and polyester carbonates. -   20. Polysulfones, polyethersulfones and polyetherketones. -   21. Cross-linked polymers deriving from aldehydes on the one hand     and from phenols, urea and melamines on the other, such as, for     example, phenol/formaldehyde resins, urea/formaldehyde resins and     melamine/formaldehyde resins. -   22. Dried or non-dried alkyd resins. -   23. Resins based on unsaturated polyesters deriving from     copolyesters of dicarboxylic acids saturated and unsaturated with     polyhydric alcohols and vinyl compounds as cross-linking agents, and     also the above resins containing halogens and having a good     flame-resistance. -   24. Cross-linkable acrylic resins deriving from substituted     acrylates such as, for example, epoxy acrylates, urethane acrylates     or polyester acrylates. -   25. Alkyd resins, resins based on polyesters or acrylated resins     cross-linked with melamine resins, resins based on urea, resins     based on isocyanates, resins based on isocyanurates, resins based on     polyisocyanates or epoxy resins. -   26. Cross-linked epoxy resins deriving from aliphatic,     cycloaliphatic, heterocyclic or aromatic glycidyl compounds such as,     for example, products of diglycidyl ethers of bisphenol A and     bisphenol F, which are cross-linked with the usual cross-linking     agents such as, for example, anhydrides or amines, in the presence     of or without accelerating agents. -   27. Natural polymers such as, for example, cellulose, natural     rubber, gelatin, and their derivatives chemically modified to give     homologous polymers such as, for example, cellulose acetates,     propionates and butyrates, or cellulose ethers such as     methyl-cellulose; as well as hydrocarbon resins (“rosins”) and their     derivatives. -   28. Mixtures of the above polymers (“polyblends”) such as, for     example, PP/EPDM, polyamides/EPDM or ABS, PVC/EVA, PVC/ABS, PVC/MBS,     PC/ABS, PBTP/ABS, PC/ASA, PC/PBT, PVC/CPE, PVC/acrylates,     POM/thermoplastic PUR, PC/thermoplastic PUR, POM/acrylates, POM/MBS,     PPO/HIPS, PPO/PA 6.6 and copolymers, PA/HDPE, PA/PP, PA/PPO,     PBT/PC/ABS, PBT/PET/PC. -   29. Natural or synthetic organic materials which are pure monomeric     compounds or mixtures of said compounds, such as, for example,     mineral oils, animal or vegetable oils, fats or waxes, oils, fats or     waxes based on synthetic esters (for example, phthalates, adipates,     phosphates, trimellitates), as well as mixtures of synthetic esters     with mineral oils in any weight ratio, in particular those used in     spinning compositions, as well as aqueous emulsions of said organic     materials. -   30. Aqueous emulsions of natural or synthetic rubbers such as, for     example, natural latex or latexes based on carboxylated     styrene-butadiene copolymers. -   31. Natural or synthetic rubbers such as, for example, acrylic     rubbers, nitrile rubbers, thermoplastic rubbers (for example, SIS,     SBS, etc.), polyisoprene, polybutadiene, polychloroprene, SBR, EPDM,     both before and after vulcanization.

The organic polymers which can be stabilized with the liquid stabilizing mixtures, object of the present invention, are, preferably, natural, semi-synthetic or synthetic polymers selected from those described above. More preferably, the liquid stabilizing mixtures, object of the present invention, are useful in the stabilization of polymers indicated above under point 30 and 31.

A further object of the present invention therefore relates to polymeric compositions containing an organic polymer and an effective quantity of one of the liquid stabilizing mixtures, object of the present invention. Yet another object of the present invention relates to the end-products obtained from the processing of the above polymeric compositions.

The liquid stabilizing mixtures, object of the present invention, are added to the organic polymers to be stabilized in a quantity ranging from 0.01% to 2.5% with respect to the weight of the organic polymer to be stabilized, preferably from 0.03% to 2%, for example from 0.1% to 1%.

The liquid stabilizing mixtures object of the present invention can optionally contain other stabilizers (co-stabilizers).

Stabilizers for organic polymers useful for the purpose are selected from the following groups:

-   1. Antioxidants -   1.1 Alkylated monophenols such as, for example: 2,6-di-t-butyl     -4-methylphenol; 2-t-butyl-4,6-dimethylphenol;     2,6-di-t-butyl-4-ethylphenol; 2,6-di-t-butyl-4-n-butylphenol;     2,6-di-t-butyl-4-isobutylphenol; 2,6-dicyclopentyl -4-methylphenol;     2-(α-methylcyclohexyl)-4,6-dimethylphenol;     2,6-dioctadecyl-4-methylphenol; 2,4,6-tricyclohexylphenol;     2,6-di-t-butyl-4-methoxymethylphenol; nonylphenols with a linear or     branched alkyl chain such as, for example,     2,6-dinonyl-4-methylphenol; 2,4-dimethyl     -6-(1′-methylundec-1′-yl)phenol;     2,4-dimethyl-6-(1′-methylheptadec-1′-yl)phenol;     2,4-dimethyl-6-(1′-methyltridec -1′-yl)phenol; and their mixtures. -   1.2 Alkylthiomethylphenols such as, for example:     2,4-di-octylthiomethyl -6-t-butylphenol;     2,4-dioctylthiomethyl-6-methylphenol;     2,4-dioctylthiomethyl-6-ethylphenol; 2,6-didodecylthiomethyl     -4-nonylphenol. -   1.3 Hydroquinones and alkylated hydroquinones such as, for example:     2,6-di-t-butyl-4-methoxyphenol; 2,5-di-t-butylhydroquinone;     2,5-di-t-amylhydroquinone; 2,6-diphenyl -4-octadecyloxyphenol;     2,6-di-t-butylhydroquinone; 2,5-di-t-butyl-4-hydroxyanisol;     3,5-di-t-butyl-4-hydroxyanisol; 3,5-di-t-butyl-4-hydroxyphenyl     stearate; bis(3,5-di-t-butyl -4-hydroxyphenyl)adipate. -   1.4 Tocopherols such as, for example: α-tocopherol, β-tocopherol,     γ-tocopherol, δ-tocopherol and their mixtures (Vitamin E). -   1.5 Hydroxylated thiodiphenyl ethers such as, for example     2,2′-thiobis-(6-t-butyl-4-methylphenol);     2,2′-thiobis-(4-octylphenol);     4,4′-thiobis-(6-t-butyl-3-methylphenol);     4,4′-thiobis-(6-t-butyl-2-methylphenol);     4,4′-thiobis-(3,6-di-s-amylphenol);     4,4′-bis-(2,6-dimethyl-4-hydroxyphenyl)disulfide. -   1.6 Alkylidene-bisphenols such as, for example:     2,2′-methylenebis-(6-t-butyl-4-methylphenol);     2,2′-methylene-bis-(6-t-butyl-4-ethylphenol);     2,2′-methylenebis[4-methyl -6-(α-methylcyclohexyl)phenol];     2,2′-methylene-bis(4-methyl -6-cyclohexylphenol);     2,2′-methylenebis(6-nonyl-4-methylphenol);     2,2′-methylenebis(4,6-di-t-butylphenol);     2,2′-ethylidenebis(4,6-di-t-butylphenol); 2,2′-ethylidenebis     (6-t-butyl-4-isobutylphenol); 2,2′-methylenebis[6-(α-methylbenzyl)     -4-nonylphenol]; 2,2′-methylenebis[6-(α,α-dimethylbenzyl)     -4-nonylphenol]; 4,4′-methylenebis(2,6-di-t-butylphenol);     4,4′-methylenebis(6-t-butyl-2-methylphenol);     1,1-bis(5-t-butyl-4-hydroxy-2-methylphenyl)butane;     2,6-bis(3-t-butyl-5-methyl-2-hydroxybenzyl) -4-methylphenol;     1,1,3-tris-(5-t-butyl-4-hydroxy-2-methylphenyl)butane;     1,1-bis(5-t-butyl-4-hydroxy-2-methylphenyl)     -3-n-dodecylmercaptobutane; ethyleneglycol     bis[3,3-bis-(3′-t-butyl-4′-hydroxyphenyl)butyrate]; bis-(3-t-butyl     -4-hydroxy-5-methylphenyl)dicyclopentadiene;     bis[2-(3′-t-butyl-2′-hydroxy-5′-methylbenzyl)-6-t-butyl-4-methylphenyl]terephthalate;     1,1-bis(3,5-dimethyl-2-hydroxyphenyl)butane;     2,2-bis(3,5-di-t-butyl-4-hydroxyphenyl) propane;     2,2-bis(5-t-butyl-4-hydroxy-2-methylphenyl)-4-n-dodecylmercaptobutane;     1,1,5,5-tetra(5-t-butyl-4-hydroxy -2-methylphenyl)pentane. -   1.7 Benzyl compounds containing O, N or S such as, for example:     3,5,3′,5′-tetra-t-butyl-4,4′-dihydroxydibenzylether;     octadecyl-4-hydroxy-3,5-dimethylbenzylmercaptoacetate;     tridecyl-4-hydroxy-3,5-di-t-butyl-benzylmercaptoacetate;     tris(3,5-di-t-butyl-4-hydroxybenzyl)amine; bis     (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate;     bis(3,5-di-t-butyl-4-hydroxybenzyl)sulfide; isooctyl     -3,5-di-t-butyl-4-hydroxybenzylmercaptoacetate. -   1.8 Hydroxybenzylated malonates such as, for example:     dioctadecyl-2,2-bis(3,5-di-t-butyl-2-hydroxybenzyl)malonate;     dioctadecyl-2-(3-t-butyl-4-hydroxy-5-methylbenzyl)-malonate;     didodecylmercaptoethyl-2,2-bis(3,5-di-t-butyl     -4-hydroxybenzyl)malonate;     bis[4-(1,1,3,3-tetramethylbutyl)phenyl]-2,2-bis(3,5-di-t-butyl-4-hydroxybenzyl)-malonate. -   1.9 Aromatic hydroxybenzyl compounds such as, for example:     1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene;     1,4-bis- (3,5-di-t-butylhydroxybenzyl) -2,3,5,6-tetramethylbenzene;     2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl)phenol. -   1.10 Triazine compounds such as, for example: 2,4-bis(octylmercapto)     -6-(3,5-di-t-butyl-4-hydroxyaniline) -1,3,5-triazine;     2-octylmercapto-4,6-bis(3,5-di-t-butyl-4-hydroxyaniline)-1,3,5-triazine;     2-octylmercapto-4,6-bis-(3,5-di-t-butyl-4-hydroxyphenoxy)-1,3,5-triazine;     2,4,6-tris-(3,5-di-t-butyl-4-hydroxyphenoxy)-1,2,3-triazine;     1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate;     1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate;     2,4,6-tris-(3,5-di-t-butyl-4-hydroxyphenylethyl) -1,3,5-triazine;     1,3,5-tris(3,5-di-t-butyl-4-hydroxyphenylpropionyl)hexahydro-1,3,5-triazine;     1,3,5-tris(3,5-dicyclohexyl -4-hydroxybenzyl)isocyanurate. -   1.11 Benzylphosphonates such as, for example:     dimethyl-2,5-di-t-butyl-4-hydroxybenzylphosphonate;     diethyl-3,5-di-t-butyl -4-hydroxybenzylphosphonate;     dioctadecyl-3,5-di-t-butyl -4-hydroxybenzylphosphonate;     dioctadecyl-5-t-butyl -4-hydroxy-3-methylbenzylphosphonate; calcium     salts of monoethyl ester of 3,5-di-t-butyl-4-hydroxybenzylphosphonic     acid. -   1.12 Acylaminophenols such as, for example: 4-hydroxylauranilide;     4-hydroxystearanilide; octyl-N-(3,5-di-t-butyl     -4-hydroxyphenyl)carbamate. -   1.13 Esters of β-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid with     monohydric or polyhydric alcohols such as, for example: methanol,     ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol,     1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol,     thiodiethylene glycol, diethylene glycol, triethylene glycol,     pentaerythritol, tris(hydroxyethyl) isocyanurate, N,N′-bis     (hydroxyethyl)oxalamide, 3-thioundecanol, 3-thiopentadecanol,     trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl     -1-phospho-2,6,7-trioxabicyclo-[2.2.2]-octane. -   1.14 Esters of 1-(5-t-butyl-4-hydroxy-3-methylphenyl)propionic acid     with monohydric or polyhydric alcohols such as, for example:     methanol, ethanol, n-octanol, i-octanol, octadecanol,     1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol,     neopentyl glycol, thiodiethylene glycol, diethylene glycol,     triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate,     N,N′-bis(hydroxyethyl)oxamide, 3-thioundecanol, 3-thiopentadecanol,     trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl     -1-phospho-2,6,7-trioxabicyclo[2.2.2 ]octane. -   1.15 Esters of β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid     with monohydric or polyhydric alcohols such as, for example:     methanol, ethanol, n-octanol, i-octanol, octadecanol,     1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol,     neopentyl glycol, thiodiethylene glycol, diethylene glycol,     triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate,     N,N′-bis(hydroxyethyl)oxamide, 3-thioundecanol, 3-thiopentadecanol,     trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl     -1-phospho-2,6,7-trioxabicyclo[2.2.2]-octane. -   1.16 Esters of (3,5-di-t-butyl-4-hydroxyphenyl) acetic acid with     monohydric or polyhydric alcohols such as, for example: methanol,     ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol,     1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol,     thiodiethylene glycol, diethylene glycol, triethylene glycol,     pentaerythtitol, tris (hydroxyethyl) isocyanurate,     N,N′-bis(hydroxyethyl)oxamide, 3-thioundecanol, 3-thiopentadecanol,     trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospho     -2,6,7-trioxabicyclo[2.2.2]octane. -   1.17 Amides of β-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid such     as, for example:     N,N′-bis(3,5-di-t-butyl-4-hydroxyphenylpropionyl)hexamethylenediamide;     N,N′-bis-(3,5-di-t-butyl-4-hydroxyphenylpropionyl)trimethylenediamide;     N,N′-bis(3,5-di-t-butyl-4-hydroxyphenylpropionyl) hydrazide;     N,N′-bis[2-(3-[3,5-di-t-butyl-4-hydroxyphenyl]propionyloxy)ethyl]oxamide     (Naugard ® XL-1 of Uniroyal) -   1.18 Ascorbic acid (vitamin C). -   1.19 Aminic antioxidants such as, for example,     N,N′-diisopropyl-p-phenylenediamine;     N,N′-di-s-butyl-p-phenylenediamine;     N,N′-bis(1,4-dimethylpentyl)-p-phenylenediamine;     N,N′-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine;     N,N′-bis(1-methylheptyl)-p-phenylenediamine;     N,N′-dicyclohexyl-p-phenylenediamine;     N,N′-diphenyl-p-phenylenediamine;     N,N′-bis(2-naphthyl)-p-phenylenediamine;     N-isopropyl-N′-phenyl-p-phenylenediamine;     N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine;     N-(1-methylheptyl)-N′-phenyl-p-phenylenediamine;     N-cyclohexyl-N′-phenyl-p-phenylenediamine;     4-(p-toluenesulfonamide)diphenyleneamine;     N,N′-dimethyl-N,N′-di-s-butyl-p-phenylenediamine; diphenylamine;     N-allyldiphenylamine; 4-isopropoxydiphenylamine;     N-phenyl-1-naphthylamine; N-(4-t-octyl-phenyl)1-naphthylamine;     N-phenyl-2-naphthylamine; di-phenylamine octylate such as, for     example, p,p′-di-t-octyldiphenylamine; 4-n-butylaminophenol;     4-butirylaminophenol; 4-nonanoylaminophenol;     4-dodecanoylaminophenol; 4-octadecanoylaminophenol;     bis(4-methoxyphenyl)amine;     2,6-di-t-butyl-4-dimethylaminomethylphenol;     2,4′-diaminodiphenylmethane; 4,4′-diaminodiphenylmethane;     N,N,N′,N′-tetramethyl-4,4′-diaminodiphenylmethane;     1,2-bis[(2-methylphenyl)amino]ethane; 1,2-bis(phenylamino)propane;     (o-tolyl)biguanide; bis [4-(1′,3′-dimethylbutyl)phenyl]amine;     N-phenyl-1-naphthylamine t-octylate; mixture of mono- and     dialkylated t-butyl/t-octyldiphenylamines; mixture of mono- and     dialkylated nonyldiphenylamines; mixture of mono- and dialkylated     dodecyldiphenylamines; mixture of mono- and dialkylated     isopropyl/isohexyldiphenylamines; mixture of mono- and dialkylated     t-butyl-diphenylamines; 2,3-dihydro     -3,3-dimethyl-4H-1,4-benzothiazine; phenothiazine; mixture of mono-     and dialkylated t-butyl/t-octylphenothiazines; mixture of mono- and     dialkylated t-octylphenothiazines; N-allyl-phenothiazine;     N,N,N′,N′-tetraphenyl -1,4-diamino-but-2-ene; N,N-bis     (2,2,6,6-tetramethylpiperid -4-yl)hexa-methylenediamine;     bis-(2,2,6,6-tetramethylpiperidin-4-yl) sebacate;     2,2,6,6-tetramethylpiperidin -4-one; 2,2,6,6-tetramethylpiperidin     -4-ol. -   2. UV ray and light stabilizers. -   2.1 Derivatives of 2-(2′-hydroxyphenyl)benzotriazoles such as, for     example: 2-(2′-hydroxy-5′methylphenyl)benzotriazole;     2-(3′,5′-di-t-butyl-2′-hydroxyphenyl)benzotriazole;     2-(5′-t-butyl-2′-hydroxyphenyl)benzotriazole;     2-[2′-hydroxy-5′-(1,1,3,3-tetramethylbutyl)phenyl]benzotriazole;     2-(3′,5′-di-t-butyl-2′-hydroxyphenyl)-5-chlorobenzotriazole;     2-(3′-t-butyl-2′-hydroxy-5′-methylphenyl)-5-chlorobenzotriazole;     2-(3′-s-butyl-5′-t-butyl-2′-hydroxyphenyl)benzotriazole;     2-(2′-hydroxy-4′-octyloxyphenyl)benzotriazole;     2-(3′,5′-di-t-amyl-2′-hydroxyphenyl)benzotriazole;     2-[3′,5′-bis(α,α-dimethylbenzyl)-2′-hydroxyphenyl]benzotriazole;     2-[3′-t-butyl-2′-hydroxy-5′-(2-octyloxycarbonylethyl)phenyl]-5-chloro-benzotriazole,     2-[3′-t-butyl-5′-(2-(2-ethylhexyloxy)carbonylethyl)-2′-hydroxyphenyl]-5-chlorobenzotriazole,     2-[3′-t-butyl-2′-hydroxy-5′-(2-methoxycarbonylethyl)phenyl]-5-chlorobenzotriazole,     2-[3′-t-butyl-2′-hydroxy-5′-(2-methoxycarbonylethyl)phenyl]benzotriazole,     2-[3′-t-butyl-2′-hydroxy-5′-(2-octyloxycarbonylethyl) phenyl     benzotriazole,     2-[3′-t-butyl-5′-(2-(2-ethylhexyloxy)carbonylethyl)-2′-hydroxyphenyl]benzotriazole,     2-(3′-dodecyl-2′-hydroxy-5′-methylphenyl)benzotriazole;     2-(3′-t-butyl-2′-hydroxy-5′-(2-isooctyloxycarbonylethyl)phenyl]benzotriazole,     2,2′-methylene-bis     [4-(1,1,3,3-tetramethylbutyl)-6-benzotriazol-2-yl-phenol];     transesterification product of     2-[3′-t-butyl-5′-(2-methoxycarbonylethyl)-2′-hydroxyphenyl]-2H-benzotriazole     with polyethylene glycol 300; [R—CH₂CH₂—COO—CH₂CH₂—]₂— wherein R═     3′-t-butyl-4′-hydroxy-5′-2H-benzotriazol-2-yl-phenyl;     2-[2′-hydroxy-3′-(α,α-dimethylbenzyl)-5′-(1,1,3,3-tetramethylbutyl)phenyl]benzotriazole;     2-[2′-hydroxy-3′-(1,1,3,3-tetramethylbutyl)     -5′-(α,α-dimethylbenzyl)phenyl]benzotriazole. -   2.2 Benzotriazoles deriving from hydantoin such as those described,     for example in patent applications EP 867,435, WO 99/23093 and WO     99/37638. -   2.3 Derivatives of 2-hydroxybenzophenones such as, for example:     4-hydroxy-; 4-methoxy-; 4-octyloxy-; 4-decyloxy-; 4-dodecyloxy-;     4-benzyloxy-; 4,2′,4′-trihydroxy-; 2′-hydroxy -4,4′-dimethoxy. -   2.4 Esters of benzoic acids, optionally substituted, such as, for     example: phenyl salicylate, 4-t-butylphenyl salicylate, octylphenyl     salicylate, benzoyl resorcinol, bis(4-t-butylbenzoyl)resorcinol,     dibenzoyl resorcinol,     2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate,     hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate, octadecyl     -3,5-di-t-butyl-4-hydroxybenzoate, 2-methyl-4,6-di-t-butylphenyl     -3,5-di-t-butyl-4-hydroxybenzoate. -   2.5 Acrylates such as, for example, ethyl or iso-octyl     α-cyano-β,β-diphenylacrylate; methyl α-carbomethoxycinnamate, methyl     or butyl α-cyano-β-methyl-p-methoxycinnamate, methyl     α-carbomethoxy-p-methoxycinnamate, N-(β-carbomethoxy-β-cyanovinyl)     -2-methylindoline. -   2.6 Nickel compounds such as, for example, Ni-complexes of     2,2′-thio-bis-[4-(1,1,3,3-tetramethylbutyl)phenol], for example 1:1     or 1:2 complexes, with or without additional ligands such as     n-butylamine, triethanolamine or N-cyclohexyldiethanolamine, nickel     dibutyldithiocarbamate, nickel salts of monoalkyl esters of     4-hydroxy-3,5-di-t-butyl-benzylphosphonic acid, such as methyl or     ethyl esters, nickel complexes with ketoximes such as 2-hydroxy     -4-methylphenyl undecyl ketoxime, nickel complexes of     1-phenyl-4-lauroyl-5-hydroxypyrazol with or without additional     ligands. -   2.7 Sterically hindered amines and their N-alkoxy derivatives such     as, for example:     poly-methylpropyl-3-oxy-[4-(2,2,6,6-tetramethyl)piperidinyl]siloxane,     polymethylpropyl     -3-oxy-[4-(1,2,2,6,6-pentamethyl)piperidinyl]siloxane,     bis-(2,2,6,6-tetramethyl-4-piperidinyl)sebacate;     bis(2,2,6,6-tetramethyl-4-piperidinyl) succinate; bis     (1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate; bis(1-octyloxy     -2,2,6,6-tetramethyl-4-piperidinyl) sebacate;     bis(1,2,2,6,6-pentamethyl-4-piperidyl)-n-butyl-3,5-di-t-butyl     -4-hydroxybenzylmalonate; condensation product between     1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and     succinic acid; condensation product, linear or cyclic, between     N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylendiamine and     4-t-octylamino-2,6-dichloro-1,3,5-s-triazine;     tris(2,2,6,6-tetramethyl-4-piperidyl)nitrilotriacetate; tetrakis     (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate;     1,1′-(1,2-ethanodiyl)bis (3,3,5,5-tetramethylpiperazinone;     4-benzoyl-2,2,6,6-tetramethylpiperidine;     4-stearyloxy-2,2,6,6-tetramethylpiperidine;     bis(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl     -2-(2-hydroxy-3,5-di-t-butylbenzyl)malonate; 3-n-octyl     -7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-di-one; bis     (1-octyloxy-2,2,6,6-tetramethylpiperidyl)sebacate;     bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)succinate; condensation     product, linear or cyclic, between     N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and     4-morpholine-2,6-dichloro-1,3,5-triazine; condensation product     between     2-chloro-4,6-di-(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1,3,5-triazine     and 1,2-bis(3-aminopropylamino)ethane; condensation product between     2-chloro-4,6-di-(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)     -1,3,5-triazine and 1,2-bis(3-aminopropylamino)ethane;     8-acetyl-3-dodecyl-7,7,9,9-tetramethyl     -1,3,8-triazaspiro-[4.5]decane-2,4-dione;     3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidin-2,5-dione;     3-dodecyl -1-(1,2,2,6,6-pentamethyl-4-piperidyl)pyrrolidin     -2,5-dione; mixture of 4-hexadecyloxy- and 4-stearyloxy     -2,2,6,6-tetramethylpiperidine; condensation product between     N-N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and     4-cyclohexylamino-2,6-dichloro-1,3,5-triazine; condensation product     between 1,2-bis(3-aminopropylamino)ethane and     2,4,6-trichloro-1,3,5-triazine, as well as     4-butylamino-2,2,6,6-tetramethylpiperidine (CAS Reg. Nr.     [136504-96-6];     N-(2,2,6,6-tetramethyl-4-piperidyl)-n-dodecylsuccinimide;     N-(1,2,2,6,6-pentamethyl-4-piperidyl)-n-dodecylsuccinimide;     2-undecyl-7,7,9,9-tetramethyl     -1-oxa-3,8-diaza-4-oxospiro[4,5]decane; reaction product between     7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa     -3,8-diaza-4-oxospiro-[4,5]decane and epichlorohydrin;     1,1-bis(1,2,2,6,6-pentamethyl-4-piperidyloxycarbonyl)-2-(4-methoxyphenyl)ethene;     N,N′-bis-formyl-N,N′-bis(2,2,6,6-tetramethyl     -4-piperidyl)hexamethylenediamine; diester of     4-methoxy-methylenemalonic acid with 1,2,2,6,6-pentamethyl     -4-hydroxypiperidine; reaction product of maleic anhydride/α-olefin     copolymer with 2,2,6,6-tetramethyl-4-aminopiperidine or with     1,1,2,2,6-pentamethyl-4-aminopiperidine. -   2.8 Oxamides such as, for example: 4,4′-dioctyloxyoxanilide;     2,2′-diethoxyoxanilide; 2,2′-dioctyloxy-5,5′-di-t-butoxanilide;     2,2′-didodecyloxy-5,5′-di-t-butyloxanilide;     2-ethoxy-2′-ethyloxanilide; N,N′-bis (3-dimethylaminopropyl)oxamide;     2-ethoxy-5-t-butyl-2′-ethyloxanilide and its mixtures with     2-ethoxy-2′-ethyl-5,4′-di-t-butoxanilide; and mixtures of     di-substituted ortho- and para-methoxy oxanilides and mixtures of     di-substituted ortho and para-ethoxy oxanilides. -   2.9 2-(2-hydroxyphenyl)-1,3,5-triazines such as, for example:     2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine;     2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)     -1,3,5-triazine;     2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine;     2,4-bis-(2-hydroxy     -4-propyloxyphenyl)-6-(2,4-dimethylphenyl)-1,3,5-triazine;     2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(4-methylphenyl)     -1,3,5-triazine; 2-(2-hydroxy-4-dodecyloxyphenyl)     -4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine;     2-[2-hydroxy-4-(2-hydroxy-3-butyloxypropyloxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine;     2-[2-hydroxy-4-(2-hydroxy-3-octyloxy-propyloxy)phenyl]-4,6-bis-(2,4-dimethylphenyl)     -1,3,5-triazine; 2-(2-hydroxy-4-tridecyloxyphenyl) -4,6-bis     (2,4-dimethylphenyl)-1,3,5-triazine;     2-[4-(dodecyloxy/tridecyloxy-2-hydroxypropoxy)-2-hydroxyphenyl]3-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine;     2-[2-hydroxy     -4-(2-hydroxy-3-dodecyloxypropoxy)phenyl]-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine;     2-(2-hydroxy-4-hexyloxyphenyl) -4,6-diphenyl-1,3,5-triazine;     2-(2-hydroxy-4-methoxyphenyl)4,6-diphenyl-1,3,5-triazine;     2,4,6-tris[2-hydroxy     -4-(3-butoxy-2-hydroxypropoxy)phenyl]-1,3,5-triazine;     2-(2-hydroxyphenyl)-4-(4-methoxyphenyl)-6-phenyl -1,3,5-triazine;     2-{2-hydroxy-4-[3-(2-ethylhexyl-1-oxy)-2-hydroxypropyloxy]phenyl}-4,6-bis(2,4-dimethylphenyl)     -1,3,5-triazine. -   3. “Metal-deactivators” such as, for example: N,N′-di-phenyloxamide,     N-salicylal-N′-salicyloyl-hydrazine, N,N′-bis(salicyloyl)hydrazine,     N,N′-bis(3,5-di-t-butyl-4-hydroxyphenylpropionyl)hydrazine,     3-salicyloylamino-1,2,4-triazole, bis(benzylidene)oxallyl     dihydrazide, oxanilide, isophthaloyl dihydrazide, sebacoyl     bisphenylhydrazide, N,N′-diacetyladipoyl dihydrazide, N,N′-bis     (salicyloyl)oxallyl dihydrazide, N,—N′-bis(salicyloyl) thiopropionyl     dihydrazide. -   4. Phosphites and phosphonites such as, for example: triphenyl     phosphite, diphenyl alkyl phosphates, phenyl dialkyl phosphites,     tris(nonylphenyl)phosphite, trilauryl phosphite, trioctadecyl     phosphite, distearyl pentaerythritol diphosphite,     tris(2,4-di-t-butylphenyl) phosphite, diisodecyl pentaerythritol     diphosphite, bis(2,4-di-t-butylphenyl) pentaerythritol diphosphite,     bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite,     diisodecyloxypentaerythritol diphosphite, bis(2,4-di-t-butyl     -6-methylphenyl)pentaerythritol diphosphite, bis     [2,4,6-tris(t-butylphenyl)]pentaerythritol diphosphite, tristearyl     sorbitol triphosphite, tetrakis-(2,4-di-t-butylphenyl)     -4,4′-diphenylenediphosphonite, 6-isooctyloxy     -2,4,8,10-tetra-t-butyl-12H-dibenzo-[d,g]-1,3,2-dioxaphosphocine,     6-fluoro-2,4,8,10-tetra-t-butyl-12-methyldibenzo[d,g]-1,3,2-dioxaphosphocine,     bis-(2,4-di-t-butyl -6-methylphenyl)methylphosphite,     bis(2,4-di-t-butyl -6-methylphenyl)ethylphosphite;     2,2′,2′-nitrilo[triethyl-tris     (3,3′,5,5′-tetra-t-butyl-1,1′-biphenyl-2,2′-diyl)-phosphite];     2-ethylhexyl-(3,3′,5,5′-tetra-t-butyl     -1,1′-biphenyl-2,2′-diyl)phosphite. -   5. Hydroxylamines such as, for example: N,N-dibenzylhydroxylamine;     N,N-diethylhydroxylamine; N,N-dioctylhydroxylamine;     N,N-dilaurylhydroxylamine; N,N-ditetradecylhydroxylamine;     N,N-dihexadecylhydroxylamine; N,N-dioctadecylhydroxylamine;     N-hexadecyl-N-octadecylhydroxylamine;     N-heptadecyl-N-octadecylhydroxylamine; N,N-dialkylhydroxylamines     deriving from hydrogenated tallow amines. -   6. Nitrons such as, for example: N-benzyl-α-phenylnitron;     N-ethyl-α-methyl-nitron; N-octyl-α-heptyl-nitron;     N-lauryl-α-undecyl-nitron; N-tetradecyl-α-tridecyl-nitron;     N-hexadecyl-α-pentadecyl-nitron; N-octadecyl-α-heptadecyl-nitron;     N-hexadecyl-α-heptadecyl-nitron; N-octadecyl-α-pentadecyl-nitron;     N-heptadecyl-α-heptadecyl-nitron; N-octadecyl-α-hexadecyl-nitron;     nitrons deriving from hydrogenated tallow amines. -   7. Thiosynergizing agents such as, for example: dilauryl     thiodipropionate; distearyl thiodipropionate. -   8. Agents which are capable of destroying peroxides such as, for     example, esters of β-thiodipropionic acid such as lauryl, stearyl,     myristyl or tridecyl esters, mercaptobenzimidazole or zinc salt of     2-mercaptobenzimidazole, zinc dibutyldithiocarbamate,     dioctadecyldisulfide, pentaerythritol tetrakis     (β-dodecylmercapto)propionate. -   9. Polyamide stabilizers such as, for example, copper salts combined     with compounds of iodine and/or phosphorous, divalent manganese     salts. -   10. Basic co-stabilizers such as, for example: melamine,     polyvinylpyrrolidone, dicyanodiamide, triallyl cyanurate,     derivatives of urea, derivatives of hydrazine, amines, polyamides,     polyurethanes, salts of alkaline metals and salts of earth-alkaline     metals of fatty acids with a high molecular weight such as, for     example, Ca-stearate, Zn-stearate, Mg-stearate, Mg-behenate,     Na-ricinoleate, K-palmitate, antimonium-pyrocatecholate,     tin-pyrocatecholate, zinc-pyrocatecholate. -   11. Nucleating agents such as, for example: inorganic substances     such as talc, metal oxides (for example, titanium dioxide or     magnesium oxide), phosphates, carbonates or sulfates (preferably of     earth-alkaline metals); organic compounds such as mono- or     polycarboxylic acids and their salts (for example, 4-t-butylbenzoic     acid, adipic acid, diphenylacetic acid, sodium succinate, sodium     benzoate); polymeric compounds such as ionic copolymers     (“ionomers”). -   12. Fillers and reinforcing agents such as, for example: calcium     carbonate, silicates, glass fibres, glass beads, asbestos, talc,     kaolin, mica, barium sulfate, metal oxides and hydroxides, carbon     black, graphite, wood flour and flours or fibres of other natural     products, synthetic fibres. -   13. Other additives such as, for example: plasticizers, pigments,     lubricants, emulsifying agents, Theological additives, catalysts,     slip agents, optical brighteners, flame-retardants (for example     bromurates, chlorurates, phosphorates and phosphorous/halogen     mixtures), antistatic agents, blowing agents. -   14. Benzofuranones and indolinones such as, for example:     3-[4-(2-acetoxyethoxy)phenyl]-5,7-di-t-butyl-benzofuran-2-one;     5,7-di-t-butyl-3-[4-(2-stearoyloxyethoxy)phenyl]-benzofuran-2-one;     3,3′-bis     [5,7-di-t-butyl-3-[4-(2-hydroxyethoxy)phenyl]benzofuran-2-one;     5,7-di-t-butyl-3-(4-ethoxyphenyl]benzofuran -2-one;     3-(4-acetoxy-3,5-dimethylphenyl) -5,7-di-t-butyl-benzofuran-2-one;     3-(3,5-dimethyl     -4-pivaloyloxyphenyl)-5,7-di-t-butyl-benzofuran-2-one; or those     described in U.S. Pat. Nos. 4,325,863, 4,338,244, 5,175,312,     5,216,052 and 5,252,643; in German patents DE 4,316,611, 4,316,622     and 4,316,876; or in European patent applications No. 589,839 and     591,102.

The above stabilizers (co-stabilizers) can be optionally added to the organic polymers to be stabilized in a quantity ranging from 0.01% to 10% with respect to the total weight of the organic polymer to be stabilized.

The incorporation of the liquid stabilizing mixtures, object of the present invention, as such or optionally in the presence of other stabilizers (co-stabilizers), in the organic polymers to be stabilized, can be carried out according to the methods known in the art, for example, before or during the processing.

The above mixtures, optionally in the presence of other stabilizers (co-stabilizers), can also be added to the organic polymers to be stabilized, either after or during polymerization or before cross-linking.

The present invention also relates to a method for stabilizing organic polymers against degradation caused by oxygen, heat and/or light, which comprises the addition of said organic polymers to the stabilizing mixtures, object of the present invention.

Some illustrative but non-limiting examples of the present invention are provided for a better understanding of the present invention and for its embodiment.

EXAMPLE 1

200 g of Anox ® BF of Great Lakes Chemical Corporation, a light yellow liquid, having a viscosity equal to 64 mPaxsec. at 50 °C. (measured with a Haake viscometer), are charged into a 500 ml reactor equipped with a stiffer and thermometer, and heated to 120°C. Anox ® BF has the structure:

100 g of drops of Lowinox ® CPL of Great Lakes Chemical Corporation are added, in 15 minutes and at 1200C., the whole mixture being maintained under stirring. After 30 minutes, the resulting amber-coloured mixture is left to cool to room temperature. Gas chromatographic (GC) analysis shows that no chemical reaction has taken place between the two compounds. Lowinox ® CPL (700-800 MW) is the reaction product of p-cresol and dicyclopentadiene, alkylated with isobutylene and has the structure:

wherein n is an integer ranging from 0 to 10.

The above gas chromatographic analysis is carried out using a Hewlett Packard 5980, series II gas chromatograph, operating under the following conditions:

-   -   T.A.P.-CB (Triglyceride Analysis Phase) capillary column made of         molten silica 50% phenyl/50% methylpolysiloxane, having a length         of 10 m, an internal diameter of 0.25 mm and a film thickness of         0.1 μm (commercialized by Crompack);     -   oven temperature program: from 70° C. to 350° C. with an         increase of 15° C./min.; final isotherm 10 min.;     -   carrier gas: helium at 3.3 ml/min.;     -   injection system: “on column”;     -   injector temperature: 73° C.;     -   detector temperature: 360° C.;     -   volume injected: 1.0 μl;     -   sample concentration: 1.0 mg/ml in toluene.

The viscosity of the mixture, measured with a Haake viscometer, is equal to 384 mPa×sec. at 70° C.

EXAMPLE 2

An aging test is carried out on samples of SBR rubber of the Europrene 1502 type, commercialized by EniChem Elastomeri using the mixture indicated in Table 1.

TABLE 1 COMPONENTS QUANTITY (%) Europrene 1502 100.0 Zinc oxide 5.0 Ultrasil VN/3 * 35.0 Glicogum 4000 ** 1.0 Titanium oxide 3.0 Sulfur 1.5 mercapto benzothiazole disulfide 2.0 Zinc dibenzyldithiocarbamate 0.2 stabilizer *** 1.0 * = type of silica; ** = ethoxylated polyethyleneglycol having a molecular weight of 4000; *** = stabilizers used indicated in Table 2 below.

TABLE 2 TEST Nr STABILIZER 1 — 2 Anox ® T * a sterically hindered phenol) 3 Lowinox ® CPL * (a polymeric sterically hindered phenol) 4 Anox ® 20 * (a sterically hindered phenol) 5 Anox ® BF * (a sterically hindered phenol) 6 Mixture example 1 (a sterically hindered phenol) *: products commercialized by Great Lakes Chemical Corporation.

The blends obtained as described above are vulcanized at 160° C. for 20 minutes obtaining rubber strips having dimensions of 200×200 mm and a thickness of 2 mm.

Standard 10 cm DUMBBELL test-samples are obtained from the above strips in accordance with regulation ASTM D412, and are subjected to aging in an oven at 100° C. Samples are taken at different times: 96 hours, 144 hours, 240 hours and 288 hours, on which the antioxidant property of the various additives is evaluated by measuring the variation in the tensile strength and elongation at break:the values obtained are indicated in Table 3 and Table 4 respectively.

TABLE 3 TENSILE STRENGTH VARIATION Test Original 96 Decay 144 Decay 240 Decay 288 Decay nr. values hours (%) hours (%) hours (%) hours (%) 1 214 203 −5.1 163 −23.8 57 −73.4 32 −85.0 2 198 195 −1.5 177 −10.6 114 −42.4 97 −51.0 3 193 174 −9.8 175 −9.3 114 −40.9 57 −70.5 4 201 213 −5.4 164 −18.4 121 −39.8 96 −52.2 5 194 208 +7.2 160 −17.5 116 −40.2 96 −50.5 6 193 212 +9.8 164 −15.0 115 −40.4 87 −54.9

TABLE 4 ELONGATION AT BREAK VARIATION Test Original 96 Decay 144 Decay 240 Decay 288 Decay nr. values hours (%) hours (%) hours (%) hours (%) 1 860 550 −36.0 415 −51.7 130 −84.9 30 −96.5 2 840 555 −33.9 450 −46.4 260 −69.0 205 −75.6 3 840 530 −36.9 450 −46.4 240 −71.4 125 −85.1 4 840 585 −30.4 425 −49.4 285 −66.1 225 −73.2 5 840 595 −29.2 440 −47.6 290 −65.5 245 −70.8 6 825 585 −29.1 455 −44.8 270 −67.3 195 −76.4

The above results demonstrate that with the liquid stabilizing mixture, object of the present invention (Test Nr. 6), the antioxidant power remains unaltered. 

1. A liquid stabilizing mixture for organic polymers or copolymers comprising: (a) a sterically hindered phenol having formula (I):

wherein: R₁ and R₂ are both t-butyl; R₃ is a linear C₁₄-C₁₆ alkyl group, (b) a sterically hindered phenol having formula (II):

wherein n is an integer ranging from 0 to 10, and the mixture is liquid both at room temperature and temperatures as low as -30°C.
 2. A process for the preparation of the liquid stabilizing mixture of claim 1 which comprises: (a′) heating a liquid compound of the sterically hindered phenol (a) to a temperature ranging from 60°C to 180°C, under stirring; (b′) adding a solid compound selected from the group consisting of the sterically hindered phenol (b), maintaining the temperature within the range of 60°C to 180°C, and maintaining the whole mixture under stirring until the complete dissolution of said compound (b), for a time ranging from 5 minutes to 100 minutes to obtain a liquid stabilizing mixture.
 3. The process according to claim 2, wherein the weight ratios between the liquid compound (a) and the solid compound (b) range from 90: 10 to 30:70.
 4. The process according to claim 2, wherein the weight ratios between the liquid compound (a) and the solid compound (b) range from 60:40 to 70:30.
 5. A liquid stabilizing mixture for organic polymers or copolymers comprising: (a) a sterically hindered phenol having formula (I):

wherein: R₁ and R₂ are both t-butyl; R₃ is a linear C₁₄-C₁₆ alkyl group, (b) a sterically hindered phenol having formula (II):

wherein n is an integer ranging from 0 to 10, and the mixture is permanently liquid both at room temperature and temperatures as low as -30°C.
 6. A liquid stabilizing mixture for organic polymers or copolymers comprising: (a) a first sterically hindered phenol having formula (I):

wherein: R₁ and R₂ are both t-butyl; R₃ is a linear C₁₄-C₁₆ alkyl group, (b) a second sterically hindered phenol comprising the reaction product of p-cresol and dicyclopentadiene, alkylated with isobutylene; wherein the mixture is liquid both at room temperature and temperatures as low as -30°C.
 7. The mixture according to claim 6, wherein the second sterically hindered phenol comprises the formula (II):

wherein n is an integer ranging from 0 to
 10. 8. A liquid stabilizing mixture for organic polymers or copolymers comprising: (a) a first sterically hindered phenol having formula (I):

wherein: R₁ and R₂ are both t-butyl; R₃ is a linear C₁₄-C₁₆ alkyl group, (b) a second sterically hindered phenol comprising the reaction product of p-cresol and dicyclopentadiene, alkylated with isobutylene; wherein the mixture is permanently liquid both at room temperature and temperatures as low as -30°C. 